Tess worries. Alot.
She was terrified of her crate. She refused to go inside. But she was (and still is) very food motivated. So, I began to feed her beside her crate - just far enough away to make her feel safe. The after a few days, I would inch it closer, repeating until after a couple weeks or so it was just inside the door.
The next stage took a bit longer. Once in the crate I inched it further into the crate - but at a much slower pace as before. Another couple of weeks. When I finally got the food dish all the way to the back of the crate, she would stretch as far as possible, keeping one paw just outside.
Once she would comfortably go completely inside the crate, I began shutting the door while she ate. I didn't lock it at this point, but she never pushed her way out, so I quickly began locking it after her. After a week of this, I began slowly leaving her in longer and longer while I stayed in the room. Then I started leaving the room and staying in the house.
Luckily, I was in college at the time, so I was usually only gone for a few hours. This way I could go back home and let her out between classes.
The whole process took over 2 months! But, with Tess, it was very important that I not ever force her into her crate. Since I am a HUGE advocate of them, it was very important that Tess feel that the crate is her "safe" place. Fast forward three years and Tess loves her crate. She often goes in just to relax (or to get away from Edi!).
That's not to say she doesn't still have issues...but we're working on it!